groups and dope

[kent]

Ok so without bragging, what are you thoughts on groups v placement at range. If a gun groups say 2" at a certain range then how do we measure its accurate and humane window of use range wise?

Shooting prone off a bipod or other rest with a butt bag under the rear say we are all going to shoot better than kneeling, improvised rested or even off hand. but lets forget about knowing our personal limits from different stances and just talk calling the shot.

You see to my mind the size of the group only relates to how well the rifle and load can work if guided correctly by the shooter add a 2" wind range call error to the 2" group in a totally constant blow holding strength (like that ever happens)and you now have 6-8" depending on how you determine the error start point.

So is it all down to feel? How sure you are of the range and how much effect the conditions prevailing? You certainly see more V bulls after two sighting shots than you do from cold clean bores in competitive shooting.

Do any actually measure their ability to shoot to an altered zero and record the info in any place other than their subconscious? Its not something I have ever done personally I admit, though it might be enlightening to see if anyone has worked their own personal factor or test into "knowing their limits"

[brown dog]

Wrote this a while back, is this the sort of thing you mean?

 

http://ukvarminting.com/forums/topic/7428-long-range-shots-and-first-round-hit-probability/

 

From Brown Dog

LONG RANGE SHOTS AND FIRST ROUND HIT PROBABILITY

The Error Budget’

Grouping ability at a given range is just one element of the issues to consider when attempting to guarantee first round hits . What's actually critical is realistic quantification of the distance between the POA and the probable POI of your first bullet. That distance is determined by a raft of variables known as the error budget.

The error budget in gunnery is extensive. Each element will affect the shooters capability to place his first shot near his POA:

Crosswind error
Rangewind error
Ranging error
Weapon cant
Weapon pointing error
MV variance
Round dispersion
Air Temp Change
Air Density variation
Angle of fire
Horizontal zeroing error
Vertical zeroing error
Sight resolution
Optical Path Bending

I shan’t consider each in detail, but it's worth observing that changing light conditions alone (ie Optical Path Bending or refraction) can move the POI vertically 0.5MOA (or left or right for a low sun).

Hit Probability and Error Discs’

Many sporting shooters fail to understand the error budget at play in hit probability and are unable to distinguish their hit probability from their ability to group.

Be clear: In shots at sporting quarry we are not talking about grouping theory or ability; we must concern ourselves with the theory of hit probability’.

As soon as you've fired your first "adjusting round" at a target you've directly measured the environmental effects; and can adjust subsequent shots accordingly…but we're not in that business with shots at game animals; the first round must have an acceptably high probability of killing humanely …- and thus first round hit probability has to be assessed realistically.

Lets say a 0.5MOA grouper at 100yds (many people mistakenly believe the group size-range relationship is linear, it is not.) prints his 0.5moa group half an inch off dead-nuts centre of his POA. His outermost round could be 0.75MOA from his POA. That's an error radius of 0.75MOA. His circular error actually subtends twice that: 1.5MOA. So, in hit probability terms, this 0.5MOA shooter actually has a circular hit probability that subtends 1.5 MOA -doesn't sound quite so cool does it?

At game animals we're in the business of guarantee; so let's round that 1.5moa to 2 moa to give ourselves an additional 0.25moa fudge factor around the tgt to allow for those 0.75moa group days

Thus, at a range the shooter can achieve 0.5MOA groups, his unadjusted hit probability actually spans a 2MOA disc over any given POA -before we consider wind!

Taking this eg to an A4 size kill zone at 400yds; firstly the disc only just fits, and secondly; you can't move it much laterally until it comes off the sheets: about 3.5"”

…..so you'd have to know your wind call is accurate to better than 3.5" of deflection to take that shot.

My Rifle Groups to 0.5MOA at 400yds, So I'm Good-to-Go with stalking shots at 400yds. Right?

You should now realise that considering your first round capability to be 0.25 MOA around your POA; because you can usually group to 0.5MOA is unrealistic in 'guarantee' terms.

Grouping ability is a measure of the rifle, not the shooter-rifle system's”ability to make first round hits under field conditions.

Once you consider the 'system' it is rarely realistic to guarantee field accuracy better than within 1 MOA of POA (ie a 2 MOA circle); and, at deer, we're talking 'guarantee'

….. and remember, 2 MOA is a guarantee level of within 1 MOA of POA, not "sometimes I can do 0.5MOA with my rifle at 400m on a no-wind range day".

How far is Too Far’?

As outlined earlier, a clever way of applying hit probability theory quickly is to visualise the killzone (as say, a piece of A4 in Landscape) and place your POA 1MOA in from the windward edge (ie even if the wind ceases, you still guarantee a kill-hit within your 2MOA system guarantee -in effect you are visualising drawing your 2MOA guarantee as a circle disc and fitting it inside the leading edge of the A4 sheet). Then determine go/no go by calculating how much wind will take any part of your 2moa 'guarantee disc' out of the leeward edge of the A4 sheet -and deciding whether you have the wind more accurately than that all the way to the target.

Pretty soon you'll realise that it's not a 'strong gust' that'll mess things up; hunting at long range it's as little as being out by a few mph on your wind call; or not noticing a wind change of only a few mph.

In order to quantify this, think of wind in terms of "inches of deflection per 1 mph change".

For example; a 308 at 400yds:


A 10mph wind will push the bullet around 14” at 400yds.

This means every 1mph change pushes the bullet 1.4 inches at 400yds.

So

Even if you are capable of grouping with a 308 to 0.0001MOA at 400 yds (and you won't be),

for every 1 mph you misjudge the wind, you will miss your POA by 1.4 inches .

Miss a 5mph wind change and your bullet goes 7 inches wide of the aiming point. Miss a 10mph change and you’re 14 inches wide.

...and that's forgetting the natural dispersion of your group compounding the error.

In Closing:

If an individual considers their deflection-per-mph-wind-change at a distance they're considering; add that to their error disc at that range and then compare that to the size of the animal's kill zone, they should quickly get an idea of what their max range should be, based on their wind reading capability.

And if anyone is claiming first round wind reading guaranteed better than to the nearest 5-10mph over unknown and broken ground they're ...err.... kidding themself.

It doesn't take much to get blown out of an animal's kill zone.

[DaveT]

I think that I understand where you are going with this...at least in a stalking context.

 

I certainly do not ever kid myself that I can repeat in the field off of cross-sticks the sort of accuracy that I can produce at the range when prone + bipod & rear bag....and all the time that I care to take over the shot!

 

When stalking I don't think that I have ever shot over 200 or so yards and usually well under that.

 

As far as range work goes I do record my 'normal' drop & windage examples (5mph / 10mph) as well as scope click variations when a mod is fitted and refer to these as I set up.

 

When dealing with 'real-life' windage I have to admit that sighters are my 'saviour' although I am trying hard to get my wind reading better and also taking note of the vertical displacement that cross-winds produce which I also have recorded in my drop tables.

 

Always more to learn unfortunately!!!

[gun nut]

Kent ,in my opinion, I think it comes down to an honest appraisal of your own abilities and lots and lots of practice that counts. There's no point having all your "practice " prone off a nice comfy lie with back bag and front rest if that's not how you shoot your deer. By practising improvised lies/rests, off sticks, up against a tree etc you will get a real world measure of your ability.

 

My personal limit is how far away I can put every bullet into a 5" circle from whatever kind of rest I can find. The range I can do this obviously varies from position to position, but at least I know what ranges i can accomplish it at. Then there are environmental conditions, when it's blowing hard or gusty it greatly reduces my ranges, but it's only by appropriate practice that I know what these limits are.

 

As far as my rifles go, both that I use for stalking group at around .5moa. Sometimes it's closer to .2" and quite often its just under the inch if I'm not really concentrating enough. This gives me immense confidence that the bullet will go where it's pointed and I think that confidence has a bigger effect on shooting game well than nearly any other factor.

 

Just my tupence worth,

 

Mike

[Offroad Gary]

Gongs!

 

Thats whats improved my competence and confidence! Instant feedback. 8" is big deer, 4" is small deer.

 

Just set them up and start wanging, all weathers, all conditions. One of the best things i've bought that has improved quite a few peoples shooting.

[onehole]

Not sure if this is what you want but I would already have done the paper target to verify I have minimum 1 !/2 inch grouping ability from my rifle at 300 yds so accuracy not a problem and I would have perfect zero set at 200 yds. I have said on other posts my ballistic charts/apps work quite well from this point in good conditions,,,,Nearly every time I go out to do some "long" range there is always time to do some practice on small rocks and larger rock faces just to see where things are going on any given day.Once you get out past 300 ish the accurate and humane window for me can vary,,,,in the very best conditions for me and my rifle I choose to do long distance with I,m happy to have a go at 600 ish and to date I have either a kll or complete miss.,,,If I see the fall of shot or a colleaque spots the hit I would have another shot if given the chance and often connected on the second shot.I am not sure whether some may call me inhumane now taking such shots but like I said I have yet to see wounded so will carry on.

To be honest I feel more comfortable sticking to around 400 yards these days and after a warm up on some bunny sized rocks or other markers I feel very confident at this range ,,certainly on a fox at that range no problem,,,,,,hope this is,nt bragging but a fox is a pretty big target at 400!!?

 

I know there are many that go a lot further out ,,,,,I don,t personally have a problem with that but I bet there are a few walked in shots beforehand?,,Onehole

[achosenman]

I think it also matters on the terminal effects of the bullet on the target. A fast expanding bullet on a smallish body sized vermin is violent and very humane in the extreme. We all know the effect I'm talking about. A hit anywhere on the body results in immediate and total destruction. The classic kill zone is somewhat moot with this scenario.

 

However when a poorly placed shot will result in a wounded animal then we must in all good conscience limit ourselves to the range that the shooter can achieve an acceptable % of a hit in the kill zone for the given animal.

 

ATB

[onehole]

Interesting to download the recent 600 yard aggregate bench rest grouping results,,,,,,,,,,,,and that's off a bench!!!!!not a bi pod off the roof of a truck ,,,,yep 600 yards is a looooong way>>>>>>>>

[achosenman]

And that's where comparisons' fall down. Both the military and competition shooters have to cope with whatever the conditions are on the day. We don't.

 

E.G I won't try long shots on a distant target if there are unfavourable conditions that work against me. I simply don't need to. I get closer or I abandon the shot. There will always be another opportunity another day.

 

ATB

[flyingfisherman]

BD, very good reading that you posted above, nice to see some very matter of fact opinions on LR on live targets. I concur with what some have said above, main thing for me is the continual (generally subconscious) assessment going on even before ive left the house regarding LR. Currency, DOPE, conditions are all in the forefront of my mind.

 

I dont do masses of LR but feel competent and current, i know my limits and work within them. If things arent right, you dont pull the trigger.

 

I still miss enough gongs at range to remind me that theres more to LR than just dialling and shooting!

[gbal]

Interesting to download the recent 600 yard aggregate bench rest grouping results,,,,,,,,,,,,and that's off a bench!!!!!not a bi pod off the roof of a truck ,,,,yep 600 yards is a looooong way>>>>>>>>[/quote

 

Your point is a good one,and has been made before- competition results are a good yardstick for what very good shooters can do with very good rifles and a very good shooting position,with probably some practice and/ or sighters at that known and exact constant distance.

Field shooters are unlikely to do consistently better.......

Gbal

[gbal]

Gongs!

Thats whats improved my competence and confidence! Instant feedback. 8" is big deer, 4" is small deer.

Just set them up and start wanging, all weathers, all conditions. One of the best things i've bought that has improved quite a few peoples shooting.

Agreed ,'bang,clang' is most satisfying.

The other outcome is 'bang,no clang' of course and that might well translate to a wounded animal.

So the benefit for shooting live targets is to keep that ratio (hit to miss) as high as possible and resist the 'I hit the gong(once)so i can shoot a deer at that distance''

Of course,good shooters know better.But the less good don't quite have to come to terms with a wild spread of holes on their target.

Or just maybe,missing the gong is effective training- do we know.

 

It does encourage people to try,and maybe therefor to learn.

[kent]

Brown Dog,

Your explanation is spot on to what I was describing. Anyone who shoots "out into the country a bit " should understand this yet its quite obvious many don't. Personally I practice (a lot) and my practice is more about positional shooting and non-sighter, non- lasered , non wind metered shooting ( I do fall foul of familiar land in that practice mind you). Reason being that's how it is in the field for me 99% of the time. Thing is I do not record the data for this in any really useful / meaningfull way, just in my head! It might be good to hear thoughts on this area? I still get it wrong every now and then and over estimate my ability to judge things and yes its quite possible to wound stuff with quite large amounts of "overkill" energy wise. Without being to graphic this happened only last week when I took the nose and upper mendable off a bunny with around 800 ft lb, it was very much alive until it was found and dispatched, considering many are shot and killed outright with 12 ft/lb airguns that might raise a few eyebrows!. I think the only thing missing off your comprehensive list is unseen grass and twigs- this has created at least half my errors, running close to that is prey movement on release of the triggers sear ( a deer / fox etc can go a long way in 0.25 second)

[hughes.s]

Like Gun nut

I work to this reguardless of range, POI from POA 1/2" for me 1/2" for the reload 1/2" for the wind and 1/2" for the rifle. If it all go"s 1 way its 2" from POI. The most important thing to me is where to place the bullet, never seen a fox with a 4" dot printed on it!. When I cant meet my own rules it"s goodnight Mr Fox catch you next time.

 

Hughes.s

[gbal]

Like Gun nut

I work to this reguardless of range, POI from POA 1/2" for me 1/2" for the reload 1/2" for the wind and 1/2" for the rifle. If it all go"s 1 way its 2" from POI. The most important thing to me is where to place the bullet, never seen a fox with a 4" dot printed on it!. When I cant meet my own rules it"s goodnight Mr Fox catch you next time.

 

 

Hughes.s

 

OK -however you put the bits together,then 2 inches will probably be in the ball park for a good shot in field conditions out to 200 yards,and may well be fine for these 4 inch kill zone foxes within that sort of distance.But beyond that ("at any range" surely not)have a look at how very good BR/f class shooters with top gear etc struggle mainly with wind,at say 600,though I'm sure you mean your method to be for short ranges. 2 moa error is good enough,and pretty good anyway you consider it,in field conditions.

As you say,tomorrrow is another day,or night!

Gbal

[hughes.s]

gbal,

The reguardless of range comment is a valid statement, but it has to be used in context with the rest of the post, I will conceed That I will never achieve it at 600yds, which then brings my last sentence into play. But I do agree with you that the formula is best used at sensible ranges. My longest shot which I do not expect to "better" is 235yds (no lamp needed) I expected the fox would be there.

 

Hughes.s

 

ps I keep re reading this and it looks a bit angry It"s not, please read it as a genuine friendly reply.

ATB Hughes.s

[gbal]

gbal,

The reguardless of range comment is a valid statement, but it has to be used in context with the rest of the post, I will conceed That I will never achieve it at 600yds, which then brings my last sentence into play. But I do agree with you that the formula is best used at sensible ranges. My longest shot which I do not expect to "better" is 235yds (no lamp needed) I expected the fox would be there.

 

Hughes.s

 

ps I keep re reading this and it looks a bit angry It"s not, please read it as a genuine friendly reply.

ATB Hughes.s[/quot

 

Ok no problems.It was just that 1/2 inch allowance for wind won't be near enough for most breezes beyond a couple of hundred yards or so,but at night 200 is getting quite a way anyhow,because of visibility,and a quick allowance like 2 inches will often be good enough for shots out to 250 anyhow,even in daylight,unless its quite breezy.The cumulative allowance for each of the likely factors is a good approach-as you are aware,the 1/2 moa rifle just won't hold an inch at 200 yards,when other factors stack up.Let alone a shaky lean on a fence post type factors....we should all be capable of good confidence for cf shots out to 200/250 yards,which is often enough...!

Atb

Gbal

 

[sonic]

I only shoot prone when load testing. I zero off the bonnet practice from the usual positions I use lamping. and have a good idea what range for any given conditions I can confidently take a fox. I will not fire if I'm not sure of a hit. not that I don't miss but I don't push my luck.

The Fox looks a bigger target than it really is all that fur makes it look bigger.

I think 2" is realistic and inch either side of poa the range varies at what this is possible due to wind etc but more win tends to mean you can get closer to mitigate it.

BD sums it up well IMO

[Crosshair]

Interesting thread. Since getting my .223 (been a .243 only man for five years but couldnt leave that slot empty forever )the other week, I've been flat out against the crows with it and I have to say, I now take a lot of the '300 yard .17hmr' stuff with a pinch of salt.

With a Swarovski z3 with brx reticle and the Swarovski app on my phone doing a great job of telling me where my bullets have dropped to and my trusty ten year old bushnell range finder telling me how far stuff is, I'm not regularly hitting crows past 250m.

The reason? Wind! Anyone who can consistently judge the stuff to within moa accuracy (and that's what you need at 300y) is a better man than me.

 

The day someone invents a 'mirage reader' that predicts wind for the full length of shot is the day I sell my rifle and buy a play station though

[brown dog]

The day someone invents a 'mirage reader' that predicts wind for the full length of shot is the day I sell my rifle and buy a play station though

http://www.oceanmedix.com/?_siteid=oceanmedix&_sessid=ef5e29090878344288f1efe0a2d023d3&action=sku&sku=dOM-racers_edge

 

What are you selling?

[Crosshair]

http://www.oceanmedix.com/?_siteid=oceanmedix&_sessid=ef5e29090878344288f1efe0a2d023d3&action=sku&sku=dOM-racers_edge

 

What are you selling?

$90,000!!!!! I think my boss would want to see a lot of dead crows for that receipt lol

[sonic]

How long before it comes down in price? just how accurate is it?

What do you do when the battery goes flat?

[achosenman]

http://www.oceanmedix.com/?_siteid=oceanmedix&_sessid=ef5e29090878344288f1efe0a2d023d3&action=sku&sku=dOM-racers_edge

 

What are you selling?

I'll take two please...just in case the battery goes flat.

[gbal]

$90,000!!!!! I think my boss would want to see a lot of dead crows for that receipt lol

$90,000!!!!! I think my boss would want to see a lot of dead crows for that receipt lol

 

While you are gasping in some of that sea air,given the price,be glad it's got some salt-accuracy is good,but at 1/2 knott,I'd be inclined to wait for the improved model for longer range seagulls!

 

Meanwhile,while we save up,for this or a playstation, you might be interested to know Brian Litz is probably on the sodium chloride diet too.I came in the otherway,243 and. 222 for decades before 223 ,so here are some data for the 243,which by almost any criteria is superior to the 223,for crows or whatever.

 

Using some of BD's super list of factors,in fact only a very few field variables,only one of which is human error(wind misjudgement-any dodgy rests,or pulled shotsare not included) the maximum effective range for the 243 given a must hit 3inch circle is just under 250yards,and for a two inch circle it is 200 yards

Beyond these distances there is a reasonable probability of a miss when the field variables all go against you- we are talking about wind speed judgement error of about 2mph,and the minor but not negligible accumulation of possible coriolis,air density/temp ,gyro drift,aerodynamic jump,and muzzle vel variation(of about plus/minus ten fps).The rifle is capable of .5 moaunder field conditions.

 

 

 

These-wind apart-are largely non negotiable.2mph wind reading is probably better than most currently can manage.

Now,of course,most shots will fall within the target circle,but not all.So we miss sometimes,even if our shooting has no faults,down to us.

Of coursei you canget a sighter on some handy rock out there and note fall of shot,you can improve subsequent shots,"walk in" is a huge help until the wind changes . But the other factors are still there.You might reload better than the fps variation,and so on,your bullets might be perfectly uniform and so on.

 

Some shooters do report walk in,or hit/miss ,but these are some of the reasons not every crow is a gonner at 300 yards.You can fairly assume that 17 hmr isn't the complete answer,either!

I expect there are some shooters who have mastered the laws of physics,or seem immune from them,in their shooting,so this is their turn to take all this theory with a pinch of salt.Crows beware!

 

Gbal

[achosenman]

An instructor once wrote “xxx sets himself low standards that he consistently fails to achieve”

 

All this talk of statistics ignores the fact that there are many examples of shots being successful at ranges far in excess of 250m. Can it be done every time? No, we are all human and all fluff a shot. I have personally witnessed shooting that was quite frankly astounding, and I don’t mean I saw a lucky shot once.

 

The man who taught me how to shoot a handgun was a Texan. He used to carry a pistol in his belt every day on his ranch just outside Houston Tx. I watched him shoot balloons at 200yds with a revolver. He shot six for six for 18 consecutive shots to prove to me that a pistol was accurate.

 

On a separate occasion I was down on the Trinity River bottom shooting Neutra rats from an airboat. We were using 22 semi autos. I pulled off a lucky long shot on a running rat at 200yds after observing where my first shot fall had struck the mud. I hit it in the head with my next shot. It was pure luck. Tom (my Texan friend) started to rib our guide. (A real life hillbilly type that lived in an old shack down there) Inevitably he rose to the bait and a challenge was issued. I kid you not; he picked up his old 22 Remington and started to shoot small birds as they flew by. I never saw him miss. We picked up 34 birds that day. Me? I can't do that plain and simple. I have never seen shooting like it and I was fresh out of the Army where I was a successful member of the shooting team.

 

My point is there are shooters out there that do not compete and have no interest in that world, but whose skill with firearms is awe-inspiring.

 

I’ve been lucky enough to meet a few over the years and just because I can’t do it, doesn’t mean it can’t be done.

 

ATB